diff mbox series

[FFmpeg-devel,1/2] avcodec/mjpegdec: fix skipping of bytes for unknown APPx markers

Message ID 20241017110012.1873-1-ramiro.polla@gmail.com
State New
Headers show
Series [FFmpeg-devel,1/2] avcodec/mjpegdec: fix skipping of bytes for unknown APPx markers | expand

Commit Message

Ramiro Polla Oct. 17, 2024, 11 a.m. UTC 
The loop to skip the remaining bytes was off by one for all markers
except for Adob.

This patch uses post-decrement instead of pre-decrement in the while
loop to make the len value easier to understand, and updates the len
value to reflect this change for the Adob marker.
---
 libavcodec/mjpegdec.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 86ec58713c..a775fdca30 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -1931,7 +1931,7 @@  static int mjpeg_decode_app(MJpegDecodeContext *s)
     }
 
     if (   id == AV_RB32("Adob")
-        && len >= 7
+        && len >= 8
         && show_bits(&s->gb, 8) == 'e'
         && show_bits_long(&s->gb, 32) != AV_RB32("e_CM")) {
         skip_bits(&s->gb,  8); /* 'e' */
@@ -1941,7 +1941,7 @@  static int mjpeg_decode_app(MJpegDecodeContext *s)
         s->adobe_transform = get_bits(&s->gb,  8);
         if (s->avctx->debug & FF_DEBUG_PICT_INFO)
             av_log(s->avctx, AV_LOG_INFO, "mjpeg: Adobe header found, transform=%d\n", s->adobe_transform);
-        len -= 7;
+        len -= 8;
         goto out;
     }
 
@@ -2162,7 +2162,7 @@  out:
     if (len < 0)
         av_log(s->avctx, AV_LOG_ERROR,
                "mjpeg: error, decode_app parser read over the end\n");
-    while (--len > 0)
+    while (len-- > 0)
         skip_bits(&s->gb, 8);
 
     return 0;